Figure 5.

Notch signaling in airways under homeostatic and regenerative conditions. (a) In homeostasis, basal cells (yellow) and ciliated cells (green) express Notch ligands. These cells maintain continuous Notch2 activation in club cells (orange) and goblet cells (purple). If Notch signaling is off, these become ciliated cells. (b) A schematic summary of the regeneration process after naphthalene or SO ₂ injury. The luminal cell loss due to injury triggers the expansion of basal cells and the direct segregation into N2ICD ⁺ club progenitors and c‐myb⁺ ciliated progenitors. Abnormal Notch activation in combination with surges of cytokines, such as IL‐4/13, induces goblet hyperplasia